The present invention relates to the making of couplers in plastic pipes.
Plastic pipes are built with belled ends for coupling with other pipes. Conventionally, these belled ends are of a larger diameter than the remainder of the pipe. This presents a problem with respect to shipping and storage of the pipes because spacers are needed between the pipes. Without these spacers, the enlarged coupling bell of each pipe is exposed to the weight of all of the pipes around it. This can easily cause damage to the bells by weakening, deforming and even cracking of the bells making them ineffective in providing a sealed coupling between the pipes.
The present invention relates to a plastic pipe from which pipe sections having male and female coupling ends are made. According to the present invention, the female coupling end, i.e. the coupling bell is consistent in diameter with the main body of the pipe. As such, when the pipe is loaded with other similar pipes without using spacers between the pipes most of the load is taken up by the pipe body rather than the coupling bell of the pipe.
In particular, a plastic pipe made in accordance with the present invention has a multiple layer wall construction comprising major wall portions which are formed with first corrugations. These major wall portions are separated from one another by minor wall portions formed with second corrugations and also formed with a bowed wall part. The second corrugations are smaller in diameter than both the first corrugations and the bowed wall part. The bowed wall part is consistent in diameter with the first corrugations.
A plastic pipe made with the above wall construction is used for forming coupleable pipe sections. This is achieved by removing a transition piece of the bowed wall part to the second corrugations. This produces a first pipe section having a coupling bell converted from the bowed wall part and a second pipe section having a male spigot formed by the second corrugations of the pipe. The male spigot fits into the bell for coupling the two pipe sections with one another.